Generally, semiconductor devices are manufactured by sequentially performing unit processes, such as deposition, photolithography, etching, ion implantation, polishing, cleaning and drying processes, on a semiconductor substrate. Among the above unit processes, the cleaning process is carried out after each unit process has been finished so as to remove the residue remaining on the semiconductor substrate. Recently, as designs tend to require a micro-sized pattern, the cleaning process has become very important.
However, impurities that remain at an edge section, a side section and a bottom section of the semiconductor substrate while the unit processes are being carried out typically are not completely removed through a general cleaning process. In order to clean the edge, side and bottom sections of the semiconductor substrate on which a metal wiring is formed, photoresist composition is coated on the semiconductor substrate, and exposure and development processes are carried out on the semiconductor substrate except for the metal wiring section. Thereafter, the semiconductor substrate is cleaned through various methods.
In a single-wafer type cleaning method, cleaning liquid is supplied to the edge section of the semiconductor substrate while rotating a vacuum chuck that grips the semiconductor substrate, thereby removing the impurities sticking to the edge section of the semiconductor substrate. In a batch type cleaning method, multiple lots of semiconductor substrates are simultaneously cleaned in a bath having the cleaning liquid therein.
However, the single-wafer type cleaning method may not effectively remove the impurities sticking to the side and bottom sections of the semiconductor substrate. In the batch type cleaning method, because the impurities separated from the semiconductor substrate float on the cleaning liquid or reside in the cleaning liquid, the impurities may reattach to the semiconductor substrate. Furthermore, the batch type cleaning method may not effectively clean the edge and side sections of the semiconductor substrate.
The impurities sticking to the surface of the semiconductor substrate may cause a process failure when performing a following process, thereby lowering the yield and productivity of the semiconductor device. In addition, because the photolithography process is required for protecting the metal wiring during the cleaning process, the manufacturing cost of the semiconductor device is increased.
Various attempts have been made to solve the foregoing problems. For example, Japanese Patent Publication No. 11-260778 (issued to Kuniyasu) discloses a single-wafer type cleaning device. Cleaning liquid is supplied to a surface of a wafer from a cleaning liquid nozzle. An ultrasonic wave is simultaneously provided by means of an ultrasonic vibration plate, thereby effectively removing the impurities from the wafer with improved cleaning of a bottom of the wafer. However, Kuniyasu's cleaning device does not selectively clean a specific portion of the wafer. U.S. Pat. No. 5,729,856 to Jang et al. discloses a cleaning device for cleaning an edge section of a wafer. U.S. Pat. No. 6,114,254 to Rolfson discloses a cleaning device in which cleaning liquid is supplied to edge and bottom sections of a wafer. However, the cleaning devices of the U.S. patents may cause a center portion of the wafer formed with a metal wiring to be exposed to the cleaning liquid.